Radio frequency identification (RFID) systems generally consist of one or more RFID readers and a plurality of RFID transponders, which are commonly termed credentials. The RFID transponder is an active or passive radio frequency communication device, which is directly attached to or embedded in an article to be identified or otherwise characterized by the RFID reader, or which is alternatively embedded in a portable substrate, such as a card, keyfob, tag, or the like, carried by a person or an article to be identified or otherwise characterized by the RFID reader. Exemplary RFID systems are disclosed in U.S. Pat. No. 4,730,188 to Milheiser (the '188 patent), U.S. Pat. No. 5,541,574 to Lowe et al. (the '574 patent), and U.S. Pat. No. 5,347,263 to Carroll et al. (the '263 patent), all of which are incorporated herein by reference.
A passive RFID transponder is dependent on the host RFID reader as its power supply. The host RFID reader “excites” or powers up the passive RFID transponder by transmitting high voltage excitation signals into the space surrounding the RFID reader, which are received by the RFID transponder when it is near, but not necessarily in contact with, the RFID reader. The excitation signals from the RFID reader provide the operating power for the circuitry of the recipient RFID transponder. In contrast, an active RFID transponder is not dependent on the RFID reader as its power supply, but is instead powered up by its own internal power source, such as a battery. Once the RFID transponder is powered up, the RFID transponder communicates information, such as identity data or other characterizing data stored in the memory of the RFID transponder, to the RFID reader and the RFID reader can likewise communicate information back to the RFID transponder without the RFID reader and RFID transponder coming in contact with one another.
The powered up RFID transponder communicates with the RFID reader by generating transponder data signals within the circuitry of the RFID transponder and transmitting the transponder data signals in the form of electromagnetic waves into the surrounding space occupied by the RFID reader. The RFID reader contains its own circuitry as well as its own reader programming, which are cooperatively designed to “read” the data contained in the transponder data signals received from the RFID transponder. It is noted that the reader circuitry and programming are typically significantly larger and more complex than the RFID transponder due to the expanded functional requirements of the RFID reader in comparison to the RFID transponder.
An essential feature of all RFID systems is that all RFID transponders and readers of a given system are sufficiently compatible to effectively communicate with one another. Compatibility is achieved in part by specifying the carrier frequency at which data signals are communicated between the RFID transponders and readers of the RFID system. There are currently two standard carrier frequencies available to RFID systems. RFID systems, which employ RFID transponders of the type conventionally termed proximity cards or proximity tags, typically communicate by means of data signals at a carrier frequency within a range of 100 to 150 kHz. This carrier frequency range is nominally referred to herein as 125 kHz carrier frequency and is deemed a low frequency. In contrast, RFID systems, which employ RFID transponders of the type conventionally termed smart cards, typically communicate by means of data signals at a higher frequency of 13.56 MHz.
At present there are many manufacturers of RFID transponders and readers. An ongoing industry-wide effort exists to further standardize RFID systems so that there is greater compatibility between RFID transponders and readers of different manufacturers. The overall objective is to more readily enable system designers and administrators to operatively integrate RFID transponders and readers of different manufacturers within the same RFID system. Examples of industry-wide standardization are ISO standards 15693 and 14443 which standardize certain aspects of RFID transponders operating at 13.56 MHz. Despite such standardization efforts, operation of most RFID systems remains dependent to some extent on proprietary programming. As a result, it remains a significant challenge to manufacture an RFID reader, which is compatible with RFID transponders from different manufacturers. The challenge is particularly acute when operation of the RFID transponders of each manufacturer are adapted to a unique set of proprietary commands, which can change over time in response to the evolving requirements for RFID systems.
While it is relatively inexpensive to periodically replace RFID transponders in an RFID system with newly-developed upgraded RFID transponders having more advanced capabilities, the same is not true for the RFID readers because of the substantial unit-cost differential between RFID readers and transponders. Thus, it is oftentimes not economically feasible to replace the RFID readers of an RFID system in response to RFID transponder upgrades. As a result, system administrators may not be able, from a cost-effectiveness standpoint, to avail themselves of upgraded RFID transponders, if the upgraded RFID transponders are incompatible with the existing RFID readers and implementation of the upgraded RFID transponders would require replacement of the existing RFID readers.
One solution to the compatibility problem is to design RFID readers, which can be periodically reprogrammed, rendering the RFID reader compatible with newly-developed upgraded RFID transponders having advanced capabilities. Reprogramming the RFID readers in these cases advantageously avoids the cost of replacing the RFID readers in their entirety. Reprogrammable RFID readers can also provide a solution to the problem of maintaining RFID system security after internal programming, such as encryption keys, has been compromised. Reprogrammable RFID readers provide a system administrator with a means for changing the compromised programming. In sum, it is apparent that reprogrammable RFID readers provide an effective, low-cost solution for maintaining the capabilities and security of an RFID system.
A relatively common application for RFID systems is to identify and authorize a person desiring access to a secured site, such as a room or other compartment, through a security entrance. The RFID reader of an RFID system employed in an access control application is fixedly positioned outside the security entrance to the secured site. The security entrance may, for example, be a security door having a mechanical lock operable by an electronic controller, which is integral with or otherwise in communication with the RFID reader. The RFID reader is typically mounted on a wall adjacent to the door or is affixed to the door itself. A user desiring access to the secured site is required to carry an ID card, which has a passive RFID transponder embedded therein. When the user approaches the security entrance, the user positions the ID card within the range of the excitation signals from the RFID reader, which elicit a responsive data signal from the RFID transponder embedded in the ID card. The RFID reader reads the resulting transponder data signal to determine if the user is a person authorized to access the secured site. If the RFID reader determines that the user is properly authorized, the RFID reader communicates an authorization signal to the electronic controller. The controller directs the mechanical lock to transition from a locked position to an unlocked position, which enables the user to open the door or which otherwise opens the door, permitting the user access to the secured site through the security entrance.
RFID systems for access control applications are oftentimes characterized by a relatively large number of RFID readers, which can be distributed across many geographically disparate and/or remote locations. RFID readers positioned in locations which lack access to an ac power line, as disclosed in U.S. Pat. No. 6,476,708 to Johnson (the '708 patent), can be powered by a self-contained portable power source within the RFID reader, such as a small disposable or rechargeable battery. If an ac power line is available, the RFID reader frequently interfaces with the ac power line via a control panel which is hard-wired to the RFID reader and the ac power line. RFID readers for access control applications are also generally housed in a secure shell or other secure enclosure to render the internal circuitry physically inaccessible to the user or unauthorized individuals and prevent tampering. In addition, RFID readers, which are coupled with a mechanical lock and electronic controller, are often physically integrated with the lock mechanism in a common housing.
The particular characteristics of RFID readers used in access control applications complicate the task of reprogramming the RFID reader. For example, the time and expense of dispatching a system administrator to each of many geographically spread out RFID readers within an RFID system to individually reprogram each RFID reader can be relatively high.
The most common method for reprogramming RFID readers used for access control applications is to connect the RFID reader directly to a computer, such as a PC, and input the new reader programming to the RFID reader via the computer. This method often requires the steps of disconnecting the RFID reader from a control panel interface, removing the RFID reader from its mounting or security shell, and/or disassembling an associated lock mechanism having the RFID reader integral therewith. Each of these steps is quite labor intensive and can significantly add to the cost of reprogramming the RFID reader. Another problem which can be faced when reprogramming a significant number of RFID readers installed at a secured facility is that, for security reasons, only one or a few of the RFID readers at the perimeter of a facility may subsequently be accessible to the system administrator, while the remaining RFID readers within the facility have become inaccessible to the system administrator.
As such, the present invention recognizes a need for an RFID system having one or more field reprogrammable RFID readers and a need for an improved method of field reprogramming the one or more of the RFID readers. Accordingly, it is generally an object of the present invention to provide an RFID system having one or more field reprogrammable RFID readers. It is generally another object of the present invention to provide a method for field reprogramming one or more of the RFID readers. More particularly, it is an object of the present invention to provide an RFID system including a plurality of RFID readers and a method for reprogramming the plurality of RFID readers, which does not require a system administrator to physically access each RFID reader. It is a further object of the present invention to provide an RFID system including a plurality of RFID readers and a method for reprogramming the plurality of RFID readers, which does not require a system administrator to individually reprogram each RFID reader.
It is another object of the present invention to provide an RFID system including an RFID reader and a method for reprogramming the RFID reader, which does not require a computer to input the new reader programming to the RFID reader. It is yet another object of the present invention to provide an RFID system including an RFID reader and a method for reprogramming the RFID reader, which is relatively secure. It is still a further object of the present invention to provide an RFID system including an RFID reader and a method for reprogramming an RFID reader, which is relatively cost-effective. It is still another object of the present invention to provide an RFID system including an RFID reader and a method for reprogramming the RFID reader, which is relatively less intrusive and/or less labor intensive than known methods and, more particularly, which eliminates or reduces the degree of physical disassembly or other physical effort required. It is yet a further object of the present invention to provide an RFID system including an RFID reader and a method for reprogramming the RFID reader, which can be completed within a predictable acceptable time period. It is another object of the present invention to provide an RFID system including an RFID reader and a method for reprogramming the RFID reader, which has an inherently low risk of error.
These objects and others are accomplished in accordance with the invention described hereafter.